This invention relates to waveguide phase shifters and, more particularly, to a phase shifter having a composite structure of series and parallel capacitive elements introducing a compensating frequency dispersive characteristic resulting in a broadband device.
Waveguide phase shifters are frequently employed in microwave circuits for shifting the phase of an electromagnetic signal in one portion of the circuit relative to such signal in another portion of the circuit. The phase shifters are constructed to introduce a phase shift of 90.degree. or other value of phase shift as is required for accomplishing the functions of the microwave circuit.
A requirement of microwave circuits is the capability of operating over a predetermined frequency band. In the case of relatively narrow band requirements, currently available phase shifters are usually sufficiently precise in their operation to provide the desired amount of phase shift at all frequencies in the operating band.
However, a problem arises in the case of broadband microwave circuits wherein the circuit functions are to be accomplished over a relatively broad band. Currently available phase shifters are frequency sensitive with the result that the amount of phase shift imparted by the shifter varies as a function of frequency over the band of interest. In broadband applications, the frequency dispersive characteristic of the phase shifter may be detrimental to the performance of the microwave circuit, particularly at frequencies near the ends of the band of operation.